We now turn to the two main non-Humean conceptions of (fundamental physical) laws, namely primitivism and dispositionalism. As its name suggests, primitivism holds that (fundamental physical) laws of nature are ontological primitives, part and parcel of the fundamental ontology of the world ([1]} is a paradigmatic example). According to dispositionalism, the laws are grounded in the fundamentally dispositional or causal nature of properties, i.e., in fundamental dispositions (see [2]}) or causal powers (see [3]}). These characterizations are rather rough and there are many metaphysical differences (and subtleties) among the various different versions of primitivism and dispositionalism, but these are not directly relevant for our focus on the spacetime aspects of these conceptions. In this perspective, the crucial common feature of primitivism and dispositionalism is that they involve some form of (irreducible) primitive modality giving rise to the spatiotemporal distribution of particular facts—both conceptions are non-reductive with respect to some modality (or with respect to the laws themselves), in stark contrast to the reductive Humean view. Within this framework, the entire Humean mosaic need not be accepted as primitive—postulating the mosaic from the start is very unsatisfying from the non-Humean point of view, since it is then not accounted for. Instead, it is derived from a proper subset of particular facts endowed with some primitive modality, which is either conferred by the primitive laws or grounded in fundamental dispositional properties.
